Various designs of hinges for use with folding apparatus are known in the art. U.S. Pat. No. 3,655,297 to Bolen, Jr. et al is typical of prior art hinges used for coupling foldable tubular parts, such as the handle of a foldable paddle. U.S. Pat. No. 3,669,133 to Hyman describes a collapsable rod that uses a cord for a joint coupling device adapted to be used with a hollow, foldable cane. U.S. Pat. No. 4,527,579 to Knotter et al. describes a foldable cane joined by pairs of hinge links having spring loaded locking sleeves. Prior art hinges do not provide a rigid, stable and safe locked joint for the foldable apparatus when the apparatus comprising the hinge is positioned for use. Prior art hinges allow the foldable device to shake and wobble when used.
A folding crutch, comprising a hinge apparatus and hinged joints, is useful to provide a means of storing or transporting a crutch when the crutch is not in use.
Numerous disclosures of folding crutch structures and related hinge apparatus have been made in attempts for useful crutch designs. For example, U.S. Pat. No. 39,854 to Wemple (1863) relates to a folding crutch for traveling or storage and having spurs on the end of the crutch to give traction on slick surfaces and a shock absorption mechanism. U.S. Pat. No. 595,637 to Kuhnke (1897) relates to a folding crutch which uses oblong plates located on the inside of each crutch pole with longitudinal slots to allow movement of the crutch sections so that the upper and lower sections can be folded flat against each other. U.S. Pat. No. 1,241,815 to Blackard (1917) relates to a folding crutch, the operation of which is attributed to two one-pivot hinges located on each of the main crutch supports and a latch on the outside of each crutch support which locks each joint in the vertical position with a snapping action. U.S. Pat. No. 2,484,406 to Gibson (1947) relates to a folding crutch having a single elongated bottom leg, attached to the main part of the crutch by means of a pivotal pin which makes its possible to fold the crutch by folding only one joint. U.S. Pat. No. 3,886,962 to Diamontis (1975) relates to a folding crutch having a pivot pin and spring loaded mechanism which enable the user to lock the crutch in position with one hand. U.S. Pat. No. 4,184,503 to Nakajima (1980) relates to a folding crutch having folding joints integrated into crutch prongs which prevent the crutch from rotating more than 180 degrees. U.S. Pat. No. 4,253,478 to Huss (1981) relates to a folding crutch and a mechanism for tightening and reinforcing the joint of a folding crutch which mechanism includes a spring loaded device that permits folding hinges to slide from a hidden and ridged position to a open and folding position.
There is a continuing need for a folding crutch, comprising a hinge apparatus, having a sturdy design and providing safe, firm and sure support for the crutch user.